Thermoplastic hydrogel impregnated composite material

Abstract

A composite material for wound dressings having a fibrous wound-contacting substrate, such as cotton gauze, impregnated with a thermoplastic hydrogel forming polymer and methods of making the same.

What is claimed is: 
     
       1. A composite material for a wound dressing comprising: (a) a fibrous wound-contacting substrate; and   (b) a thermoplastic hydrogel forming polymer selected from the group consisting of A--B--A block copolymers, multiblock copolymers, graft copolymers and polymer blends each incorporating a hydrophilic component and a hydrophobic component impregnated into said substrate.   
     
     
       2. The composite material of claim 1 wherein the thermoplastic hydrogel forming polymer exhibits microphase separation having a hydrophilic/hydrophobic domain polymer system. 
     
     
       3. The composite material of claim 1 wherein the thermoplastic hydrogel forming polymer has an equilibrium water content in the range of from about 40 to 99%. 
     
     
       4. The composite material of claim 1, wherein the A-B-A type block copolymers have hydrophobic blocks selected from the group consisting of polystyrene, poly(methyl methacrylate), polyacrylonitrile, polyesters and polyamides, and the hydrophilic blocks are selected from the group consisting of polyethylene oxide, poly(hydroxyalkyl methacrylate) and derivatives thereof, polyacrylamide, poly(N-vinyl lactam) and polyacrylic acid. 
     
     
       5. The composite material of claim 1 wherein the multiblock copolymers are selected from the group consisting of copolymers of polyacrylanitrile and hydrophilic derivatives of acrylic acid and copolymers of polyethylene oxide and lactic acid. 
     
     
       6. The composite material of claim 1 wherein the polymer blend is selected from the group consisting of a homopolymer or a copolymer of N-vinyl lactam and an acrylic copolymer containing a small proportion of acidic groups. 
     
     
       7. The composite material of claim 1 wherein the thermoplastic hydrogel forming polymer is present in an amount of from about 50 to 500% by weight based on the weight of the wound-contacting substrate. 
     
     
       8. The composite material of claim 1 wherein the wound-contacting substrate is cotton gauze. 
     
     
       9. The composite material of claim 1 wherein the thermoplastic hydrogel film forming polymer contains up to about 60% by weight of a plasticizer. 
     
     
       10. The composite material of claim 1 further comprising a water-soluble biocompatible material in the form of fine particles placed on the thermoplastic hydrogel forming polymer. 
     
     
       11. The composite material of claim 10 wherein the fine particle material is selected from the group consisting of gelatin, pectin, dextran and carboxymethylcellulose. 
     
     
       12. The composite material of claim 1 wherein the graft copolymers are selected from the group consisting of poly(N,N-dimethylacrylamide-g-styrene) and poly (2,3 -dihydroxypropyl methacrylate-g-styrene). 
     
     
       13. The composite material of claim 12 wherein the thermoplastic hydrogel forming polymer is present in an amount of from about 60 to 150% by weight based on the weight of the wound-contacting substrate. 
     
     
       14. A method of forming a composite material for a wound dressing comprising: (a) forming a solution containing a thermoplastic hydrogel film forming polymer;   (b) applying the solution to a fibrous wound-contacting substrate; and   (c) drying the solution on the fibrous wound-contacting substrate to said composite material.   
     
     
       15. The method of claim 14 wherein the solution further comprises a solvent and a plasticizer. 
     
     
       16. The method of claim 15 wherein the solution contains up to 40% by weight of the thermoplastic hydrogel forming polymer. 
     
     
       17. The method of claim 14 wherein the amount of the plasticizer is up to 60% by weight of the total weight of the thermoplastic hydrogel polymer and the plasticizer. 
     
     
       18. A method of forming a composite material for a wound dressing comprising: (a) melt processing the thermoplastic hydrogel polymer through an extruder;   (b) placing the extruded thermoplastic hydrogel polymer onto a substrate; and   (c) applying pressure to the polymer and substrate to form the composite material.   
     
     
       19. The method of claim 18 wherein the thermoplastic hydrogel polymer further comprises a plasticizer.